1. Technical Field
The present invention relate$ to a printer and a method of controlling an operation of continuously transporting printing mediums.
2. Related Art
Printers having an LD (Load) roller for supplying a printing medium into the printers and a PF (Paper Feed) roller for transporting the printing medium supplied into the printers are known as ink jet printers for performing a printing operation on a printing medium such as a sheet of regular paper (for example, see JP-A-2002-284373 and JP-A-2002-284374).
Specifically, in the printer described in JP-A-2002-284373 or UP-A-2002-264374, it is possible to continuously feed plural printing sheets by the use of the LD roller with a hopper kept in a raised state. when the plural printing sheets are continuously fed, a feed gap of the printing mediums is shortened, thereby enhancing the number of printing sheets which can be subjected to the printing operation per unit time.
However, like the printer described in JP-A-2002-264373 or JP-A-2002-284374, when the plural printing mediums are continuously fed at a high speed by the use of the LD roller with the hopper kept in the raised state, the following problems are caused. That is, plural printing mediums are continuously fed with a continuous rotation of the LD roller. As a result, the plural printing mediums are continuously fed without any gap therebetween. When the plural printing mediums are fed without any gap therebetween, the printer cannot detect a trailing end edge of the first or subsequent printing medium or cannot detect a leading end edge of the second or subsequent printing medium.
When not detecting the trailing end edge of the first or subsequent printing medium it is difficult to control the printer not to print any content on a margin of the printing medium. When not detecting the leading end edge of the second or subsequent printing medium, for example, it is difficult for the printer to adjust the time for starting the printing operation on the printing medium.
Accordingly, when the plural printing mediums are continuously fed, the printer needs to perform an inter-page control for providing a gap between the previous printing medium and the subsequent printing medium which are continuously fed.
On the other hand, the printer such as an ink jet printer performs a printing operation on the fed printing mediums while transporting the printing mediums by a predetermined amount distance). Accordingly, in the printer such as an ink jet printer, when plural printing mediums are continuously fed, it is necessary to secure a predetermined gap between the plural continuous printing mediums by the use of the inter-page control while transporting the previous printing medium under print by a predetermined distance. The printer should transport the plural printing mediums, which are continuously fed, by a predetermined distance while maintaining the gap secured by the inter-gap control.
However, when the control for transporting the printing medium under print by a predetermined distance is repeatedly performed, the gap between the plural printing mediums which are continuously fed can be easily varied. As a result, the next printing medium may be fed to a position greatly departing from a feed position expected under the control. In the continuous feed of printing mediums, the feed positions of the second or subsequent printing mediums may depart from the feed position expected under the control. The departing distance of the feed position in the continuous feed of printing mediums is great in comparison with a case where the printing mediums are fed sheet by sheet. In this way, when the feed position is greatly varied, print quality on the plural printing mediums is deteriorated. It is considered that the great variation of the feed position results form a cumulative control error due to plural times of paper feeding control after the inter-page control is performed.